Habitat: Circumpolar; Summer breeding grounds of the Greater Scaup range across the northern limits of Europe (including Iceland) and Asia, through the Aleutian Islands (year-round breeding) to Alaska (USA), and across to the Atlantic coast of Canada. It is estimated that 75% of the North American population breed in Alaska. It winters further south, reaching California, the great lakes and northern Florida in North America, the Adriatic Sea and northern Black Sea in Europe, the western Caspian Sea, and on the Pacific coast of Asia as far as south-east China.

The summer habitat is marshy lowland tundra and islands in fresh water lakes. In the fall, they start their migration south for the winter. During the winter months, they are found in coastal bays, estuaries, and sometimes inland lakes.

Status: Least Concern. Global population: 1,200,000 to 1,400,000 individuals. Populations have declined significantly since 1980. Some of the primary factors contributing to this decline are habitat loss, contaminants, changes in breeding habitat, and a lower female survival rate. Common predators of the Greater Scaup are owls, skunks, raccoons, foxes, coyotes, and humans. In most countries where Greater Scaup are hunted, a duck stamp is required along with the normal hunting licenses that are required to pursue other game. In America and Canada, waterfowl must be hunted with non-toxic shot.

Diet: Aquatic mollusks, plants, and insects. These food sources are obtained by diving underwater and eaten on the water surface. Because of the Greater Scaup’s body mass, it can dive up to 6 m (20 ft) and stay submerged for up to a minute, allowing it to reach food sources that are unobtainable to other diving ducks

Nesting: Great Scaups have blue bills and yellow eyes and is 20% heavier and 10% longer than the closely related Lesser Scaup. Distinguishing Greater from Lesser scaups can be extraordinarily difficult in the field, especially in terms of plumage, although (depending on posture) their general shape is slightly different.

The male has a dark head with a green sheen, a black neck, breast and tail, a light back and its belly and flanks are a bright white, sometimes with gray vermiculations on the lower flanks. The drake also has a white speculum on its wings. The drake or male Greater Scaup is larger and has a more rounded head than the female.

The Greater Scaup drake's eclipse plumage looks similar to its breeding plumage, except the pale parts of the plumage are a buffy gray.

The adult female has a white band and brown oval shaped patches at the base of the bill, which is a slightly duller shade of blue than the drake's bill. Females have grey on both their legs and feet. They have a brown body and head, with white bands on their wingtips.

Juvenile Greater Scaup look similar to adult females.

Drake Greater Scaup have a soft quick whistle to get the attention of hens during their courtship which takes place from late winter to early spring, on the way back to their northern breeding grounds. Female Greater Scaup have a single pitch, a raspy “arrr-arrr-arrr-arrr-arrr” sounding vocalization. The courtship procedure is complex and results in the formation of monogamous pairs. After the female lays the eggs, the drake abandons the female. Once the drakes leave the females, they go to a large, isolated lake, in order to molt.

They nest near water, typically on islands in northern lakes or on floating mats of vegetation. They begin breeding at age two, but start building nests in the first year. The nest consists of a shallow depression made by the female and lined with her own down feathers. Females lay a clutch of six to nine olive-buff colored eggs. The eggs hatch in 24 to 28 days. The down-covered ducklings are able to follow their mother in her search for food immediately after hatching.

Cool Facts: Occasionally an older female Greater Scaup will have male-like head color and male patterning on her back, but she still has the typical white face patch of a female.

The nest of a Greater Scaup is usually lined with a thick layer of down plucked by the mother from her own breast. Nests of poor-condition females may lack down and instead may contain small, grayish-white feathers plucked from beneath the outer body feathers.
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A large group of Scaups on the water (which can number up to 1,000 individuals) is called a “raft”.